The measurement of utilities in asthma patients: a preliminary study. [Abstract]

Objectives: To assess the feasibility of a computer-based Standard Gamble (SG) visual prop whilst measuring utilities of different asthma health states at the same time.
Methods: Twenty adult asthma patients literate in either Malay or English language were conveniently sampled from a public hospital in Penang, Malaysia. They were interviewed by two trained interviewers using a bilingual script. Each patient was requested to value the given health states using Visual Analogue Scale (VAS) prior to SG exercise. There were three chronic health states (C1-C3) for 10 years, three temporary states (T1-T3) for 3 months, and two anchor states (healthy and dead). During the SG exercise, the visual prop was fully operated by the interviewers. The probability of being in a worse state was changed in a ‘ping-pong’ fashion until the indifference point was reached.
Results: All patients understood the SG exercise and rated SG easier than VAS. Around 85% (n=17) completed SG within 30 minutes. There was 90% (n=18) who ranked T3 as the worst temporary health state during VAS. Two patients provided logical inconsistency data in SG. The preferences by SG were higher than VAS. Preferences were also higher in temporary states measured by chained SG than other states by conventional SG. The mean utilities for C1=0.56 (SD 0.38), C2=0.47 (SD 0.33), C3=0.53 (SD 0.38), T1=0.65 (SD 0.31), T2=0.53 (SD 0.35), and T3=0.38 (SD 0.38).
Conclusions: The SG methods including the props are feasible for utilities measurement in asthma, based on the agreements achieved with other studies on the pattern of utilities measured in this preliminary study.